Nonbounce switch



June 3% 11953 W. A. MARTEN 2@@4@9@52 NONBOUNCE swnca Filed Feb 2, 1951 270 rneys Patented June 30, 1953 NONBOUNCE SWITCH Wilbert A. Martin, Freeport, Ill., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application February 2, 1951, Serial No. 209,123

17 Claims. 1

This invention relates to improvements n electrical switches.

Electrical switches commonly include a stationary contact and a movable contact adapted to be moved into and out of engagement with the stationary contact. A serious problem in such switches, and particularly in snap acting switches, arises from contact bounce which occurs when the moving contact strikes the stationary contact. Ihis bouncing of .the movin contact against the stationary contact has several deleterious effects. Each time the moving contact bounces, an arc is drawn between it and the stationary contact, resulting in excessive heating of the contacts and transfer of contact material from one contact surface to the other. This, in turn, results in lowering the current carrying capacity of the switch and in shortening the contact life, along with possible faulty operation of the electrical circuits controlled by the switch.

An object of this invention is to provide a switch construction designed to overcome contact bounce.

Further objects of this invention are to provide a switch of high current carrying capacity, to provide a switch which may be made subminiature in size, and to provide, a switch having a high resistance to acceleration.

Further objects and advantages of this invention will be apparent from a consideration of the following description, together with the drawing, wherein there is explained a preferred embodiment of the invention.

In the drawings:

Figure 1 is a longitudinal sectional view of a snap acting switch embodying the present invention, with the movable contact in one position;

Fig. 2 is a similar View of the same switch, with the movable contact having been displaced to its opposite position;

Fig. 3 is a top view of the switch blade which supports the movable contact;

Fig. 4 is aperspective view of the compression spring member of the snap acting mechanism of the switch;

Fig. 5 is a perspective view of one of the stationary contacts of the switch;

Fig. 6 is a perspective view of the plunger which actuates the snap acting mechanism in the switch;

Fig. 7 is an enlarged side view showing the stationary contact, the movable contact, and the resilient support for the movable contact 2 at the instant of engagement between the movable and stationary contacts;

Fig. 8 is a similar view showing the parts when the supporting blade for the movable contact is at its extreme limit of movement shortly after contact has been made, and

Fig. 9 is a similar view at an instant later when the blade forsupporting the movable contact has rebounded away from its extreme limit of movement.

The switch mechanism is enclosed in a housing comprising an insulating base I and an insulating cover 2. Stationary switch contacts 3, 4 are secured in opposed spaced relation adjacent one end of the base by means of rivets 5, 6, whose outer ends are connected to external terminals 1, 8. The snap acting spring mechanism in the switch includes a switch blade 9 mounted at one end in cantilever fashion by a rivet Iii extending through aperture ii therein and connected to an external terminal 12. If desired, electrical terminals 1, 8, i2 may be formed integral with the respective rivets 5, t and It. An anchor member at is likewise secured by rivet I ll to extend below the switch blade, offset therefrom for most of its length. A washer I i encircles the rivet above the switch blade. Spring member I5 is bowed in compression between the anchor and the switch blade, and the movable switch contact I5 is afiixed to the switch blade adjacent its free end. The ac tuator for the snap acting spring mechanism is here shown as a plunger I! passing through the housing and engageable with the switch blade intermediate the length of the latter to initiate the snap action movement of the movable contact.

As best seen in Fig. 3, switch blade c includes' a solid leaf spring portion 9a extending from the mounted end at H and being of less width than the mounted end to form a reduced neck portion. Neck portion 9d at its end remote from the mounted end merges into a bifurcated leaf spring portion formed by arms I8, IS, on which are formed transverse inner protrusions 20, 2| serving as seating surfaces for one end of the compression spring member. Spaced leaf springs 22, 23 serve as flexible, resilient extensions of arms l8, l9 forwardly of protrusions 2%, 2! and these terminate in a transverse portion 24 interconnecting their outer free ends. Another leaf spring arm 25 is secured to crosspiece 24 and extends between members 22, 23 and terminates in a position closely adjacent, but spaced from, shoulders 2o, 2!. Adjacent its 3 free end, arm 25 is formed with an aperture 26 for receivin a contact rivet. Preferably, the entire switch blade is of integral, coplanar construction, formed from a single piece of flat spring material.

From Fig. 4 it will be seen that the compression spring member is of tapered leaf-spring construction, longitudinally bowed into an approximately U shape. At its wide end the compression member is cut away at its periphery to form shoulders 21, 28 and an outwardly bent tongue 29. At its narrow end the compression member is bent outwardly to form a tongue 30. When the spring members are assembled, the compression member extends freely between the arms l8, 19 of the tension member, with tongue 38 pivotally seated in a transverse groove 3| formed in the free end of anchor It. At its other end, tongue 29 extends freely between arms i8, is in abutting relationship with protrusions 2B, 2!, with shoulders 21, 28 resting on arms 18, I8 and the bent tongue at bearing against and extending slightly beneath the protrusions to prevent disengagement of the compression spring at this end.

It will be noted that the distance between pivotal groove 3| and protrusions 29, 21 is short, so that the compression spring l is also relatively short. Because of this, the compression spring exerts a force much more nearly perpendicular to the plane of tension member 8 than would be the case if the compression spring were longer. This results in a more forceful snap movement of the snap spring system.

It will also be noted thatthe perpendicular force exerted by compression spring 15 is applied to the tension member 9 at the protrusions 28, 2 I, which are spaced rather close to'movable contact 2%. This is an important aspect in the bounce preventing characteristics of the device, as will be more readily apparent hereinafter.

The snap-spring actuator l? includes a stem 32 surmounted by a pimple 33 and having at its inner end a transverse cross member for engagement with the snap spring. This cross member is formed with a ridge on its face remote from stem 32. A bearing 35 in the switch housing permits reciprocation of the actuator, and by engaging the side walls of cross member 34 prevents the same from turning. Interior transverse ridges 3! formed in the side walls of the switch housing are interposed in the path of reciprocation of cross member 3% to limit inward movement of the actuator, in order to prevent excessive overtravel of contact blade 9.

In operation, when actuator I? is depressed, ridge 35 has line contact with the solid neck portion 9a of the switch blade at roughly midway between the mounted end I l of the switch blade and the bifurcated portion thereof It, (9. This solid neck portion 9a is relatively stiff because of its solid form, so that a force applied intermediate its ends results in a movement of its free end without an objectionable amount of lost motion due to flexibility of the switch blade itself. The actuator engages the switch blade transversely thereacross to eliminate transverse buckling or tilting thereof, and this renders the switch blade more certain in its movement. When thus engaged by the actuator, switch blade 9 is deformed until the upward force exerted by compression spring I5 against the free end of the switch blade is overcome by the tension in arms (8, l9 and neck 9a. The switch blade moves through the axis of maximum stress to move with a snap action the outer ends of arms l8, H! (at protrusions 28, 2 l) to the other side of a plane passing through the mounted end I l of the switch blade and the pivotal groove 3| for compression spring 15. Extensions 22, 23 and cantilever arm 25 also move with a snap action to displace movable contact 16 from engagement with the upper stationary contact 3 (Figure 1) into engagement with the lower stationary contact 6 (Figure 2).

By suitably locating anchor groove 3 l, in which the compression member is pivotally seated, the switch blade 9 and the movable contact 26 will snap back to their original position, when the force on actuator H is removed, by Virtue of the downward force exerted by the compression member upon the switch blade being overcome as a result of the straightening of the switch blade 9 upon removal of the actuating force. This selfreturn aspect of the snap spring system, while desirable in many instances, may be omitted without departing from the spirit of this invention.

The lower stationary contact member 4 is shown in detail in Fig. 5, and includes a flat mounting portion 38 having a hole 39 permitting reception of the rivet 8. The contact surface is formed by a finger lll bent upwardly above the plane of portion ll, which is offset from the mounting portion.

As is apparent from Figs. 1 and 2, each stationary contact preferably has its contact surface inclined at an angle to the plane of the contact blade in the undisplaced position of the latter, both contact surfaces extending inwardly toward the contact blade in a direction toward the mounted end thereof.

The previously described construction of switch blade 9 provides for a resilient mounting of movable contact it, by virtue of the resiliency of extensions 22, 23 and of arm 25. The bifurcated construction of the tension member at l3, l9 adds still further to the resiliency of the snap spring system. Normally contact carrying arm 25 is biased to be coplanar with the tension member and with extensions 22, 23.

Figs. 7-9 illustrate the action of the movable contact mounting when the movable contact is moved into engagement with the upper fixed contact. From these figures it will be apparent that after movable contact l6 strikes the upper stationary contact 3 the tendency for the movable contact to bounce is opposed by the overtravel of resilient arms 2'2, 23 which continue in the same direction. At this instant the energy which would normally be dissipated in the bouncing of movable contact 16 against the fixed contact is instead absorbed by the displacement of contact carrying arm 25 out of its natural coplanar relationship with arms 22, 23 and in resistance offered to further overtravel of the contact blade. After reaching the maximum limit of overtravel, the switch blade tends to rebound in the direction of the contact carrying arm 25. However, it has been found that the arms 22, 23 do not rebound beyond the plane of contact carryin arm 25 even though arms 22, 23 rebound and oscillate back and forth quite violently. Thus, there is always energy stored in resilient arm 25 urging the movable contact if; into engagement with fixed contact 3, and the contacts do not separate even though the movable contact rocks vigorously on the fixed contact.

It will be noted that the compression spring 15 at this position of the movable contact it exerts an upward force against the switch blade which is substantially directly opposed to the rebound force of furcations I8, 22 and I9, 23. This opposing force exerted bythe compression spring is applied against the switch blade at protrusions 20, 2|, which are positioned close to the movable contact it. Ihe relatively short arms [8 plus 22 and I9 plus 23 are unable to rebound with sulficient force, when thus opposed by the force of the compression spring Iii, to rebound below the movable contact.

Several factors will be recognized as contributing to this result:

The relatively short lengths of the flexible arms I8 plus 22 and [9 plus 23 tend to limit their rebound;

The short length of compression spring enables the force exerted by it to be substantially perpendicular to the switch blade to directly oppose the rebound;

The movable contact [6 is flexibly and resiliently mounted by means of cantilever'leaf spring arm 25, which faces in a direction toward the mounted end of switch blade 9, so that upon overtravel of the switch blade the movable con tact mounted on the free end of arm 25 rocks about the fixed contact while continually maintaining engagement therewith; and

The opposing force of the compression spring is applied to the switch blade closely adjacent the movable contact 16 to more effectively oppose the rebound of arms l8 plus 22 and i9 plus 23.

In addition the inclination of the contact surface of the fixed contact is of considerable importance. It will be noted that the area on movable contact it at which it engages the movable contact 3 is positioned away from the mounted end of cantilever leaf spring arm.25 with respect to the position of the center of mass of movable contact 58. Because of this, a torque is exerted on the movable contact tending to move it in the same direction in which it is pulled by the force exerted by its spring arm 25 (because of the displacement of the latter out of its natural coplanar relationship with arms 22, 23). Because this torque and the spring force do not opposite each other, the movement of the movable contact over the contact surface of the fixed contact is smooth. In the illustrated example, this movement consists of a rollingaction of the curved movable contact [6 over the fiat contact surface of fixed contact 3, and separation f the contacts during thisaction is avoided.

While the sloping construction of the fixed contacts is particularly advantageous in connection with the present device, it is to be understood that considerable improvement over prior constructions of this type is obtained merely by employing the novel snap spring and movable contact carrier with parallel, spaced fixed contacts or stops, the latter arrangement of parallel stops being common in this type of device.

A similar rebound-preventing action takes place at the lower stationary contact t when actuator I i is depressed to snap the movable contact into engagement with the lower contact.

Switches may be made according to the present invention to be enclosed in a housing whose outside dimensions are approximately inch by 4 inch by inch. At a continuous current of 5 amperes the temperature rise will not exceed 30 degrees centigrade. The switch can sustain a momentary surge current of 12 amperes. It has a resistance to acceleration of approximately sixty times the acceleration due to gravity for each the snap position in either direction. These switches can be employed to control circuits up to 230 volts A. C. or 28 volts D. C. The mechanical life of these switches is also quite satisfactory.

While a preferred embodiment of the invention has been described in detail above, it will be understood that various changes may be made from the specific form illustrated without departing from the spirit of the invention.

I claim:

1. In a switch-mechanism having a fixed stop, a switch blade havinga fixedly mounted portion and a portion remote from its mounted portion free to move past said fixed stop between alternate positions, means to exert a force at said movable portion of the switch blade having a substantial component perpendicular to said switch blade for moving said movable portion of the switch blade past said fixed stop, a resilient extension connected to said movable portion of the switch blade and extending therebeyond in'a directionaway from said mounted end of the switch blade, and contact carrying means resiliently connected to said extension and extending back toward the mounted portion of the switch blade and carrying a mobile contact disposed in close proximity to said movable portion of the switch blade at which said force is exerted, said means for exerting said force against said movable portion of the switch blade being operative to move the latter in one direction past said fixed stop to move said mobile oontact into engagement with said fixed stop and being operative after such engagement to continue to exert said force in the same direction to restrain said movable portion of the switch blade and said extension from rebounding back to the other side of said fixed stop so as to thereby oppose rebound of the mobile contact away from said fixed stop.

2. In a switch mechanism having a fixed contact, a switch blade having a fixedly mounted portion and an end remote from its mounted portion movable between opposed positions, means to exert a force at the movable end of the switch blade having a substantial component perpendicular thereto in response to deformation of another portion of the switch blade, a fiexible resilient extension connected to said movable end of the switch blade and extending therebeyond in a direction away from said fixedly mounted portion thereof, and a contact carrying member resiliently connected to said extension and extending toward the mounted portion of the switch blade, said contact carrying member carrying a mobile contact at its free end, said mobile contact being positioned on said contact carrier to be moved into engagement with said fixed contact when said force is exerted against the switch blade in a direction toward said fixed contact to move the switch blade with a snap action and being positioned adjacent that portion of the switch blade at which said force is exerted so that said force is exerted against the switch blade at a location and in a direction to oppose rebound of the mobile contact away from said fixed contact.

3. In a switchmechanism having a fixed contact, a switch blade mounted at one end and having a portion remote from its mounted end free to move between opposed positions with a snap action, means stressed in compression interconnected with said switch blade for exerting a force thereagainst at said movable portion remote from the mounted end, said force having a substantial component perpendicular to said switch blade, a

resilient member connected to said movable portion of the switch blade and extending therebeycnd in a direction away from said mounted end thereof, and a contact carrying member resiliently connected to said extension and extending toward the mounted end of the switch blade and carrying a mobile contact, said mobile contact being positioned on said contact carrying member to be moved into engagement with said fixed contact when said compression means exerts a force against the switch blade in a direction toward said fixed contact for moving said movable portion of the switch blade with a snap action in said direction and being disposed closely adjacent that portion of the switch blade at which said compression means exerts its force so that said compression member exerts said force against the switch blade at a location and in a direction to oppose rebound of the mobilecom tact away from said fixed contact.

4. In a switch mechanism, the combination of a fixed contact, a switch blade mounted at one end and having a portion remote from its mounted end free to move past said fixed contact with a snap action, means stressed in compression interconnected with said switch blade for exerting a force thereagainst at said movable portion thereof, said force having a substantial component perpendicular to said switch blade for moving said movable portion thereof past said fixed contact, a resilient bifurcated leaf spring member connected to said movable portion of the switch blade and extending therebeyond in a direction away from said mounted end thereof and having its remote ends interconnected by a transverse bridging portion, a resilient leaf spring member cantilevered at one end to said bridging portion and extending back toward the mounted end of the switch blade and terminating at its free end in a contact carrying portion located in 1 close proximity to said movable portion of the switch blade against which said force is exerted, and a mobile contact mounted on said contact carrying portion and positioned thereon to engage said fixed contact when said force is exerted against the switch blade for moving said movable portion of the switch blade in one direction past said fixed contact, said compression means being operative to exert said force against said movable portion of the switch blade to move the latter past said fixed contact and to move said mobile contact into engagement with said fixed contact and being operative after such engagement to continue exerting said force in the same direction to prevent said movable portion of the switch blade and said bifurcated leaf spring member from rebounding back to the other side of said fixed contact, so that the mobile contact is restrained against bounding back away from said fixed contact.

5. In a switch mechanism, in combination, a fixed contact, an elongated leaf spring mounted at one end and having its other end free to move between opposed positions, a compression spring member interacting with said leaf spring to exert a perpendicular force against the free end thereof, means for engaging said leaf spring to effect movement of the free end thereof with a snap action, a resilient extension connected to said free end of the leaf spring and extending therebeyond in a direction away from the mounted end of the leaf spring, a movable contact carrying member flexibly and resiliently connected to said extension, said movable contact member extending toward the free end of the leaf spring and terminating in a contact carrying portion disposed in close proximity to the free end of the leaf spring against which said perpendicular force is exerted, and a mobile contact mounted on said contact carrying member and positioned thereon to engage said fixed contact when said perpendicular force is exerted against the free end of the leaf spring in a direction toward said fixed contact for moving said free end of the leaf spring in said direction with a snap action, said mobile contact being positioned in close proximity to said free end of the leaf spring against which said force is exerted, so that said force is exerted at a location and in a direction to oppose rebound of the mobile contact away from said fixed contact when the mobile contact is moved into en agement with the fixed contact.

6. In a switch mechanism having a fixed contact, a tension member mounted at one end and having its other end free to move between opposed positions, a compression member interconnected at one of its ends with the free end of the tension member and stressed in compression to exert a force thereagainst having a substantial component perpendicular to the tension member, at least one of said members being resilient, a resilient extension connected to the free end of the tension member and extending therebeyond in a direction away from said mounted end of the tension member, a movable contact carrier flexibly and resiliently connected to said extension and extending back toward said free end of the tension member, and a mobile contact mounted on the carrier at the end thereof disposed adjacent said free end of the tension member at which said force is exerted, said mobile contact being positioned on said contact carrier to engage said fixed contact when said compression member exerts said force against said free end of the tension member in a direction toward said fixed contact to move said free end of the tension member in said direction, said mobile contact being located in close proximity to said free end of the tension member so that said force is exerted '5 against said free end of the tension member at a location and in a direction to oppose rebound of the mobile contact away from said fixed contact upon movement of the mobile contact into engagement with the fixed contact.

'7. In a snap acting switch having a fixed contact, a tension member mounted at one end and having its other end free to move between opposed positions, a compression member connected to the free end of the tension member and stressed in compression between the free end of the tension member and a point in fixed spaced relation from the mounted end of the tension member to exert a force against the free end of the tension member having a substantial component perpendicular to the tension member, at least one of said members being resilient, a resilient extension formed on said tension member beyond the free end thereof extending in a direction away from the mounted end of the tension member, a movable contact carrying member flexibly and resiliently connected to said extension, said movable contact carrying member being formed with a contact carrying portion disposed toward the free end of the tension member, and a mobile contact carried on said contact carrying member and positioned thereon to engage said fixed contact when said compression member exerts a force on said free end of the tension member in a direction toward said fixed contact to move said free end of the tension member in free end of the tension member so that said forceis exerted on said free end of the tension member at a location and in a direction to oppose rebound of the mobile contact away from said fixed contact following said snap action movement of the free end of the tension member.

8. A snap switch comprising a fixed contact, a tension member mounted at one end and having its other end free to move between opposed positions, a compression member interconnected at one of its ends with the free end of the tension member and stressed in compression to exert a force thereagainst having a substantial component perpendicular to the tension member, at least one of said members being resilient, a resilient extension connected to the free end of the tension member and extending therebeyond in a direction away from said mounted end of the tension member, a movable contact carrier flexibly and resiliently connected to said extension and extending toward said free end of the tension member, a mobile contact mounted on the carrier at the end thereof disposed toward said free end of the tension member, means for effecting relative movement between the other end of the compression member and a portion of the tension member to cause said compression member to exert a force against said free end of the tension member in a direction toward said fixed contact to move said free end of the tension member in said direction with a snap motion, said mobile contact being positioned on said contact carrier to engage said fixed contact upon said snap motion of the free end of the tension member, said mobile contact being located in close proximity to said free end of the tension member so that said force exerted by the compression member against the free end of the tension member for causing said snap motion thereof is applied and directed to oppose rebound of the mobile contact away from said fixed contact following said snap motion of the free end of the tension member.

9. In a switch mechanism having a fixed contact, a tension leaf spring mounted at one end and having its other end free to move between opposed positions, said tension leaf spring being bifurcated at its free end and formed with an elongated solid portion extending between its mounted and free ends, a short compression spring pivotally interconnected with the free end of the tension spring and stressed in compression between said free end and a point in fixed spaced relation from the mounted end of the tension spring to exert a force perpendicular to the tension spring at the free end thereof, a resilient bifurcated second leaf spring member connected to the free end of the tension. spring and extend ing therebeyond for a short distance in a direction away from the mounted end of the tension spring, the ends of the furcations of said second leaf spring member remote from the tension member being interconnected by a bridging portion, a resilient third leaf spring member cantilevered at one end to said bridging portion and extending back toward the free end of the tension spring, said third leaf spring terminating short of the free end of the tension spring in a contact carrying portion, means for effecting relative movement between a portion of the tension spring and the end of the compression spring remote from the free end of the tension spring to cause said compression spring to exert a force against the free end of the tension spring in a direction toward said fixed contact for moving said contact carrying portion in said direction with a snap action, and a mobile contact carried on said contact carrying portion and located thereon to be moved into engagement with said fixed contact upon said snap action movement of said contact carrying portion, said mobile contact being located closely adjacent the free end of the tension spring 'so that said compression spring exerts said force against the tension spring in a direction to oppose rebound of the mobile contact away from the fixed contact following said snap action movement of the con.- tact carrying portion.

10. In a switch mechanism having a fixed contact, a tension leaf spring mounted at one end and having its other end free to move between opposed positions, said tension leaf spring being bifurcated at its free end and formed with an elongated solid portion extending between its mounted and free ends, a short compression spring pivotally interconnected at one of its ends with the free end of the tension spring and stressed in compression to exert a force against said free end substantially perpendicular to the tension member, a short resilient bifurcated sec ond leaf spring member connected to the free end of the tension spring and extending therebeyond in a direction away from the mounted end of the tension member and having its furcations remote from the tension memberinterconnected by a transverse bridging portion, a resilient third leaf spring member cantilevered at one end to said bridging portion and extending back toward the free end of the tension spring, said third leaf spring terminating short of the free end of the tension spring and formed with a contact carrying portion closely adjacent the free end of the tension spring, all said leaf springs being normally biased into co-planar relationship, a mobile contact positioned on said contact carrying portion to be moved into engagement with said fixed contact, and a reciprocable plunger engageable with said elongated solid portion of the tension spring intermediate the length thereof to move the same relative to the other end of the, compression spring to cause said compression spring to exert a force against the free end of the tension spring in a direction toward said fixed contact to effect movement of the contact carrying portion with a snap action toward said fixed contact, said mobile contact being mounted in close proximity to said free end of the tension spring so that said force exerted by the compression spring against the free end of the tension spring for causing said snap action movement of the contact carrying portion is located and directed to oppose rebound of the mobile contact away from said fixed con tact.

11. In a switch mechanism, in combination, an elongated tension leaf spring mounted at one end and having its other end bifurcated and free to move between opposed positions, oppositely positioned, inwardly extending transversely protruding portions formed on the furcations at the free end of the tension leaf spring, an anchor member formed with a groove extending transversely of the tension leaf spring at the bifurcated portion thereof in spaced relation from the transversely protruding portions, a compression leaf spring pivotally seated at one end 'in said groove and having its other end pivotally engaging said transversely protruding portions, said compression leaf spring being longitudinally bowed to pass freely between the furcations of the tension leaf spring and being stressed in compression between its pivotal engagements to exert a force against the free end of the tension leaf spring substantially perpendicular thereto, a resilient bifurcated leaf spring member con" nected to the free end of the tension leaf spring and extending therebeyond and having its remote ends interconnected by'a transverse bridging portion, a resilient leaf spring arm cantilevered at one end to said bridging portion and extending toward the tension leaf spring and terminating at its free end in a contact carrying portion disposed adjacent the free end of the tension leaf spring, and means for engaging the tension spring at a portion thereof disposed toward its mounted end, with respect to the pivotal groove in the anchor member, to move said portion of the tension spring past said pivotal groove, whereby to effect movement of said contact carrying portion with a snap action.

12. In a switch mechanism, in combination, an elongated tension leaf spring mounted at one end and having its other end bifurcated and free to move between opposed positions, oppositely positioned, inwardly extending transversely protruding portions formed on the respective furcations at the free end of the tension leaf spring, an anchor member formed with a groove extending transversely of the tension leaf spring at the bifurcated portion thereof in spaced relation from the transversely protruding portions, a tapered compression leaf spring formed with an outwardly bent tongue at its narrow end pivotally seated in the anchor groove and formed at its wide end with an outwardly bent tongue disposed between aligned transverse shoulders, said shoulders at the wide end of the compression leaf spring abutting the furcations at the free end of the tension leaf spring and said bent tongue at the wide end of the compression leaf spring extending beneath the transversely protruding portions at the free end of the tension leaf spring to form a pivotal engagement between said compression and tension leaf springs, said compression leaf spring being longitudinally bowed to pass freely between the furcations of the tension leaf spring and being stressed in compression between its pivotal engagements to exert a force against the free end of the tension leaf spring substantially perpendicular thereto, a resilient bifurcated leaf spring member connected to the free end of the tension leaf spring and extending therebeyond coplanar therewith and having its remote extremities interconnected by a transverse bridging portion, and a resilient leaf spring member connected at one end to said bridging portion and extending toward the tension leaf spring and formed with a contact carrying portion at its other end disposed adjacent the free end of the tension leaf spring.

13. In a switch mechanism, in combination, an elongated leaf spring mounted at one end and having its other end free to move between opposed positions, means for effecting movement of the free end of said leaf spring with a snap action, a resilient extension connected to the leaf spring at its free end and extending therebeyond in a direction away from the mounted end of the leaf spring, a movable contact flexibly and resiliently connected to said extension, said movable contact being disposed toward the free end of the leaf spring and being formed with a curved contact face, and a fixed contact posi- 12 tioned adjacent the movable contact and formed with a contact face interposed in the path of movement of said movable contact inclining to ward the leaf spring in a direction toward the mounted end thereof, said contact face on the fixed contact being cooperable with said curved contact face on the movable contact to permit said movable contact to roll thereon when said,

movable contact is moved into engagement with said fixed contact.

14. In a snap acting switch, a tension member mounted at one end and having its other end free to move between opposed positions with a snap action, a compression member interconnected at one of its ends with the free end of the tension member and stressed in compression thereagainst to exert a force having a substantial component perpendicular to the tension member at the free end thereof, at least one of said members being resilient, a resilient extension connected to the free end of the tension member and extending therebeyond in a direction away from the mounted end of the tension member, a movable contact carrier flexibly and resiliently connected to said extension and terminating in a contact carrying portion disposed adjacent the free end of the tension member, a fixed contact positioned adjacent said contact carrying portion and interposed in the path of movement thereof, said fixed contact being formed with a contact face inclining inwardly toward said extension in a direction toward the mounted end of the tension member, and a mobile contact mounted on said contact carrying portion formed with a curved contact face having a portion offset from the center of mass of the mobile contact in a direction toward the mounted end of the switch blade positioned to initially engage the contact face of the fixed contact when said mobile contact is moved into engagement with the fixed contact upon snap action movement of the free end of the tension member, said curved face of the mobile contact being cooperable with said contact face of the fixed contact to roll thereon upon flexing of said contact carrier relative to said extension after movement of the mobile contact into engagement with the fixed contact.

15. In a switch mechanism, in combination, a switch blade mounted at one end and having a portion remote from its mounted end movable between opposed positions with a snap action, means stressed to exert a force against said switch blade at said movable portion thereof having a substantial component perpendicular thereto, a resilient extension connected to said movable portion of the switch blade and extending therebeyond in a direction away from the mounted end of the switch blade, contact carrying means resiliently connected to said extension and extending toward the switch blade and formed with a contact carrying portion disposed toward that portion of the switch blade at which said stressed means exerts its force, a fixed contact positioned adjacent said contact carrying portion and interposed in the path of movement of said contact carrying portion. said fixed contact being formed with a contact surface inclining toward said extension in a direc tion toward the mounted end of the switch blade, and a mobile contact mounted on said contact carrying portion formed with a curved contact face cooperable with said contact surface of the fixed contact to roll thereon when said mobile contact is moved into engagement with the fixed 13 contact upon snap action movement of said movable portion of the switch blade.

16. A snap switch comprising a tension member mounted at one end and having its other end free to move between opposed positions with a snap action, a compression member interconnected at one of its ends with the free end of the tension member and stressed in compression to exert a force thereagainst having a substantial component perpendicular to the tension member, at least one of said members being resilient, a resilient extension connected to the free end of the tension member and extending therebeyond in a direction away from the mounted end of the tension member, a movable contact carrier flexibly and resiliently connected to said extension and extending back toward the tension member, a movable contact mounted on the carrier at the end thereof disposed toward the tension member, a pair of opposed, spaced, fixed contacts positioned adjacent said movable contact in the respective paths of movement thereof on opposite sides of the carrier, each said fixed contact being formed with a contact surface inclining inwardly toward the carrier in a direction toward the tension member, means for effecting relative movement between the other end of the compression member and a portion of the tension member to move the movable contact between the fixed contacts with a snap action, said movable contact being formed with curved contact faces at opposite sides of the carrier, each said curved contact face on the movable contact being cooperable with the contact surface of the respective fixed contact to roll thereon upon flexing of said contact carrier relative to said extension following movement of the movable contact into engagement with said fixed contact.

17. In a switch mechanism, a switch blade mounted at one end in cantilever fashion and portion, a flexible resilient leaf spring cantile-' vered at one end to said bridging portion and extending between the furcations of the extension leaf springs back toward the switch blade and terminating at its free end in a contact carryin portion disposed adjacent said free end of the switch blade, said switch blade, extension leaf spring, and contact carrying leaf spring all being biased to be normally coplanar, a fixed contact positioned adjacent said contact carrying portion and interposed in the path of movement thereof, said fixed contact being formed with a contact surface inclining toward the plane of said switch blade in a direction toward the mounted end thereof, and a mobile contact mounted on said contact carrying portion and formed with a curved contact face cooperable with said contact surface on the fixed contact to roll thereon when said cantilevered spring flexes following movement of the mobile contact into engagement with the fixed contact.

VVJLBERT A. MARTIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,334,769 Huetten Nov. 23, 1943 2,370,479 Meyer Feb. 27, 1945 2,463,891 Malone Mar. 8, 1949 2,475,820 C'oake July 12, 1949 

